1. Field of the Invention
This invention relates to contact or impact force distribution devices. In particular this present invention is a force distributing device inserted between an impact applying surface and an impact receiving surface for intercepting the impact and distributing the impact over a larger surface.
2. Prior Art
In the contemporary manufacture of motor vehicles, a transmission with clutch assembly is used to transmit power and direction to the drive wheels of the motor vehicle, the power being generated by an engine or a motor. A casing, which covers the transmission and becomes a transmission/casing assembly, provides a friendly work environment for the transmission. Within the friendly work environment, the transmission, which includes a clutch plate assembly, is subjected to several forces, such as heat, pressure and rotational or torque forces. Some of these forces are imparted to the casing providing the friendly work environment surrounding the transmission. Buffer elements such as bearings, plates and rings are selectively positioned between the transmission and the casing to insulate the casing from application of some of these forces that may cause damage to the casing. The function of the casing is to contain the work friendly environment about the transmission while the transmission does the actual work of transmitting power and direction of that power from the engine or other power supply to the drive wheels of the vehicle. The transmission parts such as gears, shafts, plates and accessory elements are, for the most part, fabricated from strong, hard metal, such as steel, for example. The casing, which is defined by a relatively large envelope, is normally fabricated from a less strong, less hard material such as a compound of aluminum, for example. Not only is the casing fabricated from a softer material and easier to fabricate than the elements of the transmission but the casing material is substantially less expensive. This reduces substantially the over-all cost of a complete transmission/casing assembly.
As is well known, steel has a much higher wear resistance than the wear resistance of the aluminum compound used for fabricating a casing for retaining the work environment for a steel component transmission, which it surrounds. Part of the transmission assembly is a plurality of clutch plates which includes flat ring plates with external splines, normally called pressure plates, interposed with flat ring plates with internal splines, normally called friction plates. This plurality of plates is subjected to torque. The torque is imparted to the interior walls of the casing by the external splines on the pressure plates. The external splines on the pressure plates extend.into channels in the interior wall of the casing. The purpose for extending the external splines into the channels of the casing is for arresting the externally splined pressure plates from rotation. The internal splines of the friction plates connect to the transmission. This arrangement is employed in a transmission and casing assembly manufactured by the General Motors Corporation and identified as a Power Glide (TM) transmission. The pressure plate with extending splines is usually fabricated from a spring steel and may be from approximately 0.0675 of an inch to 0.2025 of an inch in thickness. The pressure plate/friction plate assembly, or clutch plate assembly is supported on the upper flat surface of an hydraulic cylinder or piston in the interior of the casing. In its finction as a clutch assembly, the externally splined pressure plates are held stable, that is, arrested from rotating at all times. This is accomplished by providing a plurality of spaced, recessed channels about the periphery of the interior of the casing, each channel extending both above and below the upper surface of the hydraulic piston. The externally extending splines of the pressure plates are positioned in the channels and captured, arresting the pressure plate from rotating. The internal splines of the friction plates extend into slots in the transmission and rotate with the transmission when the hydraulic piston is relaxed, that is, there is no application of pressure or compression force on the clutch plate assembly, so that the pressure plates are stable and the friction plate, spaced between the pressure plates, rotate with the transmission. When the hydraulic piston is exerted, the piston presses against the clutch plate assembly, and the pressure plates and friction plates are pressed together, applying a rotational force or torque to the pressure plates. In arresting the pressure plates from rotation by holding the externally extending splines in the channels of the interior of the casing, the rotation energy or torque is imparted to the walls of the channels of the casing by the splines making a striking contact with the walls of the recessed channels in the casing. Continued striking contact between the external splines of the pressure plates and the walls of the channels in the casing, damage the casing. Damage to the casing leads to destruction of the casing with loss of the friendly work environment for the transmission. Loss of the friendly work environment leads to destruction of the transmission.
The present invention provides an improved motor vehicle transmission/casing assembly in which a buffer element, for intercepting and distributing energy, is interposed between a torque driven element and the casing of the transmission. The torque driven element is the externally extended spline on the pressure plate of the clutch plate assembly. The part of the casing assembly by which the energy is intercepted is the wall of the channel into which the external spline of the pressure plate extends. The buffer element is interposed between the exterior of the spline in contact with the wall of the casing and the wall of the casing. The buffer element is preferably fabricated from a very hard material, such as spring steel, for example while the casing of the transmission is fabricated from a substantially soft material such as aluminum, for example. The buffer element intercepts energy from the external splines of the torque driven pressure plate of the clutch assembly, receiving the energy in a small area of the buffer element. The buffer element absorbs the energy and distributes the energy throughout its mass and transfers or delivers the distributed energy to the casing over a substantially large area of the casing. The buffer element, in its preferred embodiment, takes the form of a loose liner which covers a portion of the interior walls of the channel in the casing, particularly the portion of the walls in the channel, extending from a position in the casing above the level, in the casing, where the top pressure plate of the clutch plate assembly lies, to below the surface of the hydraulic piston in relaxed position in the interior of the casing. The channel terminates, at its low end, at a point in the casing which is somewhat below the level of the surface of the hydraulic piston, with the piston in relaxed position. Each flat ring plate with the external splines, or pressure plate, is normally fabricated from spring steel having a thickness of from 0.0675 of an inch to 0.2025 of an inch. The buffer element is preferably fabricated from spring steel having a thickness of 0.015 of an inch. A spring steel to spring steel contact is made when a torque is applied to the clutch plate assembly. This contact is made at a very small area on the buffer element. When the buffer element transfers the energy of the contact to the interior surface of the casing, the transfer is made over a substantially large surface of the casing. The positioning of the external splines in the buffer element hold the buffer member in the channel of the casing. The lower end of the channel, below the position of the upper surface of the piston, is terminated just below the level of the top of the piston, when the piston is relaxed. This channel termination keeps the buffer element from sliding in the direction of the piston, here assumed to be the lower direction in the casing. In order to keep the buffer element in position in the channel, that is to keep the buffer element from sliding out the channel, upwardly, a groove is made in the interior wall of the casing, which approximates the level of the top of the buffer element. A snap ring is engaged in the groove and prevents the buffer element from moving up the channel. This combination keeps the buffer element in position in the channel in the interior of the casing, holding the buffer element relatively loosely in the channel.
The present invention provides an improved transmission/casing assembly with an energy distribution member, which receives energy, in the form of torque, absorbs the energy, distributing the energy throughout the mass of the energy distribution member and transfers the energy over a larger surface to surface contact than originally received. This distribution and transfer of torque by a relatively loosely retained buffer element, avoids damage to the assembly casing due to constant contact between the external splines of the pressure ring of the clutch plate assembly and the wall of the internal channel arresting the pressure ring from rotation, when the pressure plate of the clutch plate assembly is subjected to a torque.